From help-request at octave dot org Thu Jul 14 05:18:27 2005
Subject: Re: basic DLD help?
From: Shai Ayal <shaia at biocontrol dot co dot il>
To: "John W. Eaton" <jwe at bevo dot che dot wisc dot edu>
Cc: David Bateman <David dot Bateman at motorola dot com>,         Paul Kienzle <pkienzle@users.sourceforge.net>, help@octave.org
Date: Thu, 14 Jul 2005 13:22:19 +0300

Ah,

but what if I do want to change the data ?

Shai

John W. Eaton wrote:
> On 13-Jul-2005, David Bateman wrote:
> 
> | Even better would be
> | 
> |    const RowVector y(args(0).vector_value());
> |    const double *py = y.fortran_vec();
> | 
> | since as you say fortran_vec calls make_unique except when "const", and 
> | since you aren't altering the data past to the function, in this manner 
> | you avoid a copy.
> 
> Still better would be
> 
>   const RowVector y(args(0).vector_value());
>   const double *py = y.data();
> 
> because if you are only asking for read-only access, you can use the
> const data() method and avoid the call to make_unique().
> 
> As I recall, the reason for having different names (fortran_vec and
> data) was because it was not possible to overload on const in early
> C++ dialects.  Now that it is possible, I suppose we could use just
> one name instead of two.
> 
> jwe
> 



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